Synthesis of Li2sio3 Using Novel Water Assisted Solid State Reaction Method

Journal of the Ceramic Society of Japan 125 [6] 472-475 2017 Full paper

Synthesis of Li2SiO3 using novel water-assisted solid state reaction method

Mizuki WATANABE, Jun INOI*, Sun Woog KIM**, Tatsuro KANEKO, Ayano TODA, Mineo SATO*, Kazuyoshi UEMATSU, Kenji TODA³, Junko KOIDE***, Masako TODA***, Emiko KAWAKAMI***, Yoshiaki KUDO***, Takaki MASAKI**** and Dae Ho YOON****,³³

Graduate School of Science and Technology, Niigata University, Niigata 950–2181, Japan *Department of Chemistry and Chemical Engineering, Niigata University, Niigata 950–2181, Japan **Department of Nanotechnology and Advanced Material Engineering, Sejong University, 209 Neungdong-ro, Gwangjin-gu, Seoul 05006, Republic of Korea ***N-Luminescence Corporation, 8867–3 Ikarashi 2-nocho, Niigata 950–2101, Japan ****School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 400–746, Republic of Korea

Single phase of orthorhombic Li2SiO3 was synthesized via a novel soft-chemical synthesis method, water assisted solid state reaction method at 343353 K for 60 min. The crystal structure of the samples was characterized by X-ray diﬀraction (XRD) analysis. The scanning electron microscope (SEM) observation revealed that the estimated size of the particles is 50200 nm. The XRD patterns and SEM images were compared to those of samples by a conventional solid state method at 1173 K for 4 h. ©2017 The Ceramic Society of Japan. All rights reserved.

Key-words : Alkali silicate, Li2SiO3, Soft chemistry, Ionic diffusion, Water

[Received December 22, 2016; Accepted March 17, 2017]

ceramics particles synthesized by the SSR method is only micro- 1. Introduction scale size with granular morphology, because the method requires Alkali metal oxidesilica binary systems, M2OSiO2 have been high-temperature calcination, resulting in particle growth im- used as a base material of traditional glass without long-distance mensely. Applications of the surface reaction as the CO2 captures order, called “amorphous”. In particular, alkali-silica reaction and lithium battery cathode materials require more small parti- (ASR) in concrete, firstly reported in 1940, is one of the well- cles, causing high surface area.17) In addition, many synthesis 1)4) known inorganic reactions. Driving force of cement harden- methods of Li2SiO3 have been studied including precipitation ing is a hydration reaction by addition of water, leading to method, solgel method, and hydrothermal method. However, dissolution - precipitation. The fine product after hydration has most of the time, a mixture of Li2SiO3,Li2Si2O5,Li4SiO4 and 16),18)20) large surface area and their OH bond, hydrogen bond, and SiO2 was obtained. Therefore, more reactive new synthe- van der Waals force result in cohesion force and adhesion force. sis method is required. ASR secondarily occurs between reactive silica in concrete In this study, we synthesized successfully single phase of well- aggregates and an alkaline solution and causes the formation of crystalline lithium metasilicate Li2SiO3 by a novel soft chemical hydrated alkali silicate gel in the micro pores of concrete. synthetic method, water assisted solid state reaction (WASSR) 21) On the other hand, Li2OSiO2 ceramics with the long-distance method. The WASSR method is a very simple and low cost order have attracted much attention, because of their func- method, specifically synthesizing many ceramic materials just by 5),6) tional properties, such as tritium breeding materials, CO2 storing a mixture of raw materials added a small amount of water captures,7),8) ionic conductors,9) and lithium ion battery materi- in closed containers at low temperature, ranging under 373 K 10),11) als. Among of them, alkali metasilicate Li2SiO3 has been without any strong acid/base and organic solvent and equipment, actively investigated as luminescent material,12),13) lithium battery multi steps, and liquid waste disposal, as compared with other materials,14),15) and optical wave guides.16) solution methods. Wide variety of ceramic materials synthesized Li2SiO3 is generally synthesized by a conventional solid state by WASSR method can be obtained as fine on submicron- and reaction (SSR) method at high temperature. This method exhibits nano- scale particles, because the reaction between the raw mate- large distributions in terms of morphological and size controls rials proceeds at low temperature (below 373 K), caused by a of the particle achieving wider application of ceramic materials; small amount of water, compared to the conventional SSR method. ³ @ Corresponding author: K. Toda; E-mail: ktoda eng.niigata-u. 2. Experiment ac.jp ³³ Corresponding author: D. H. Yoon; E-mail: [email protected] A stoichiometric ratio mixture (0.5 g) of orthorhombic LiOH· ³³³ Preface for this article: DOI http://doi.org/10.2109/jcersj2.125.P6-1 H2O (0.4664 g, Kojundo Chemical Laboratory Co., Ltd., Sedi- ³³³³ Publication of this international collaborative article is mentation type, amorphia, 2N) and amorphous SiO2 (0.3339 g, supported by JSPS Grants-in-Aid for Scientific Research Kanto Chemical Co., Inc., 3N) was mixed using a mortar for (KAKENHI), Grant Number 252016 1 min. A small amount of de-ionized water was added to the mix-

ture in a ratio of 10 wt %. The samples were put in a polystyrene estimated at 3.9 © 10¹4, 2.5 © 10¹4, 11.9 © 10¹4 nm¹2, respec- container, and stored at 353 K for 10180 min in an automatic tively. In case of sample obtained by WASSR method, the oven (Yamato Scientific Co., Ltd. DKN 302). For comparison of intensity ratio of the facets became large in increasing order of Si the size and morphology of Li2SiO3 particles, Li2SiO3 was also ratio in the facets; the Li exposes in the (020) and (111) facet more + prepared by the SSR method. A stoichiometric ratio mixture of widely than the (200) facet. Li in the lattice in obtained Li2SiO3 ¹ LiOH·H2O and SiO2 was prepared by mixing a mortar with attracts OH in raw material LiOH·H2O. Consequently, the Li- acetone for 15 min. The mixture was heated at 1173 K for 4 h in rich facets increasingly grow. The Si-rich facet (200), therefore, air. Powder X-ray diffraction (XRD) data were obtained using an grows more slowly. In contrast, the intensity ratio of the facets X-ray diffractometer (MX-Labo, Mac Science Ltd.). The particle in the sample obtained by the SSR did not follow the order of ¹ morphologies were observed by a scanning electron microscope Si ratio, because OH in LiOH·H2O acting as driving force of (SEM, JSM-5310MVB, JEOL Ltd.). growth of Li-rich facet lost under high-temperature condition in the SSR method. 3. Result and discussion In case of the conventional SSR method, the calcination at Figure 1 shows the XRD pattern of the Li2SiO3 samples high temperature is absolutely necessary to promote a reaction prepared by the WASSR method, ranging from 323353 K, and between raw materials in a system, because ionic diffusion rate SSR method. The standard XRD pattern of the orthorhombic in a solid, becomes faster with the increase of the heat which Li2SiO3 structure with the space group of Cmc21 (No. 36) the system receives from Arrhenius equation. On the other hand, obtained from the inorganic crystal structure database (ICSD in the WASSR method, the reaction proceeds below 373 K, as #16626) is also shown in Fig. 1 as a reference. The SSR method following possible reason. Figure 3 describes the schematic sample had an impurity of monoclinic Li4SiO4 phase with the diagram of the hypothesis of the reaction mechanism for the space group of P121/m1 (No. 11). The Li2SiO3 samples stored WASSR method. A small amount of water added to raw-material over 353 K for 60 min are well indexed to the single phase of mixture acts as a reaction accelerator. The water covers the sur- orthorhombic Li2SiO3; the samples stored below 333 K for face of the raw materials particle, forming thin layer of water 60 min were raw material LiOH·H2O phase. Under the high- around the particles; the concrete value of thickness of water temperature condition (over 343 K), the dehydration of LiOH· layer, unfortunately, is unexplained. H2O is promoted; the dehydration temperature of LiOH·H2Ois Because of this water layer, the reaction between raw materials near 373 K. The dehydrated H2O which acts as a driving force is accelerated at a contact point of the particles. After the reaction of the reaction in the WASSR method (discussed below) might at the contact point, the target material particles move in the water accelerate the reaction. As a result, the reaction rate increases at layer, resulting in consecutive appearance of new reactive points, higher temperature. The samples obtained by the WASSR because convection occurs in the water layer, caused from the method exhibits a broader peak with full width at half maximum reaction heat. In the SSR method, the reaction heat diffuses to air. (FWHM) [0.4214: 16.5223 degree of the (200) XRD peak], com- In contrast, in the WASSR method the reaction heat diffuses in pared to FWHM [0.2529: 16.5699 degree of the (200) XRD the water layers. Because the reaction heat assists the reaction, peak] of the sample obtained by the SSR method, as shown in Fig. 1. In addition, the X-ray intensity ratio of samples obtained by the WASSR method is different from the reference pattern based on the ICSD. Especially, the (200) XRD peak is larger than the (020), (111) XRD peak. This indicates the (200) facet growth more slowly than other facets. The difference in growth rate is caused by difference in the proportion of Li and Si in the facets. Figure 2 shows plane of (020), (111), and (200) of orthorhombic Li2SiO3 crystal structure. Table 1 exhibits the ratios of Si4+ in the crystal structure in (020), (111), and (200) plane and the FWHM at each peaks. The ratios of Si4+ ion in (020), (111), and (111) plane were

Fig. 2. The crystal structure of (a) orthorhombic Li2SiO3, (b) plane (020), (c) plane (111), and (d) plane (200) of Li2SiO3.

4+ Table 1. The ratios of Si in (hkl) in the Li2SiO3 crystal structure and peak intensity in (hkl) of samples obtained by the SSR method and WASSR method at 353 K for 60 min, deeming the peak intensity in (002) as 1 Peak intensity ratio (hkl) Ratio of Si4+ (nm¹2) SSR WASSR Fig. 1. The XRD patterns of Li SiO synthesized (ad) by the WASSR 2 3 (020) 3.9 © 10¹4 11 method, storing LiOH·H O and SiO with 10 wt % water in closed 2 2 (111) 2.5 © 10¹4 0.6 1.3 container at 323353 K for 60 min and (e) by the SSR method, heating at (200) 11.9 © 10¹4 1.2 0.8 1173 K for 4 h.

473 JCS-Japan Watanabe et al.: Synthesis of Li2SiO3 using novel water assisted solid state reaction method

ceramic materials synthesized by the WASSR method. The low- temperature solid state reaction could provide the moderate crystal growth of Li2SiO3 the lattice. In our previous study, YVO4 could be synthesized by the WASSR method at room temperature.21) Total amount of dissolution of Y2O3 and V2O5 raw materials in water, according to these results, was negligibly small in WASSR method, judging from the aqueous solubility of Y2O3 (0.018 g/L at 25°C) and V2O5 (0.7 g/L at 25°C). In a case of Li2SiO3, total amount of dissolution of SiO2 raw material in water was also negligibly small [aqueous solubility of SiO2 (0.33 g/L at 353 K)], although total amount of dissolution of LiOH (142 g/L at 323 K) are large. Because total amount of dissolution of SiO2 was small, the reaction between LiOH·H2O and SiO2 is not solution reaction using dissolvable raw materials, such as hydrothermal, solgel, and precipitation reaction. The mechanism of WASSR method is probably diﬀerent from Fig. 3. A schematic diagram of a hypothesis of the reaction mechanism the ASR, although both reactions require water as driving force for the WASSR method. each reaction. The powders caused from ASR are amorphous without long-distance order. The following general equation suggested:23) ð Þ þ þ ð Þþ Ca OH 2 SiO2 Na OH H2O

! n1Na2O n2CaO n3SiO2 n4H2O ðgel-type productÞ

However, in the WASSR method, Li2SiO3 could be obtained using alkali hydroxide and SiO2, as is the case of ASR. Tentative equation of the reaction in the WASSR method is similar to the reaction of the SSR method, as below:

LiOH H2O þ SiO2

! Li2SiO3 ðcrystalline powderÞþH2O" A small amount of water added to raw-material mixture covers the surface of the raw material particle, forming thin layer of water around the particles. This water layer, solid acid-base reaction between raw materials is accelerated at a contact point of Fig. 4. The SEM images of raw materials grinded for 1 min, (a) ortho- the particles. In fact, the WASSR and the ASR require water as ff rhombic LiOH·H2O and (b) amorphous SiO2 and the Li2SiO3 particles driving force, however, the roll of water is obviously di erent. obtained by (c) the WASSR method, storing at 353 K for 60 min and The water in the WASSR method is used not solvent for dis- (d) the SSR method, heating at 1173 K for 4 h. solution of raw materials, but as new contact points of the raw material particles by conveying of synthesized Li2SiO3 particle. the WASSR method could synthesize ceramics materials at 4. Conclusion far lower temperature, compared to the solid state reaction. All Alkali metasilicate Li2SiO3 could be synthesized as single target material particles in one system, as shown under side in phase by the novel WASSR method over 343 K. The mechanism Fig. 3, form minuscule droplet of water. Eventually, the water is probably different from the ASR in concrete. Further studies dries off and the agglomerated nanoparticles remain. In our pre- on the mechanism of the WASSR method are in progress and will vious work, the size of the aggregations was 100200 nm, reveled be reported elsewhere. In addition, the particle size of Li2SiO3 by SEM observation.21),22) The particle size of most of the obtained by the WASSR method is smaller, ranging from 50 to ceramic materials synthesized by the WASSR method is less than 200 nm, compared with that of SSR method. This method is 100 nm without reference to the particle size of raw materials. promising technique for an industrial application for ceramic In case of Li2SiO3, raw materials, orthorhombic LiOH·H2O materials synthesis, due to their low-temperature and low-cost and amorphous SiO2 grinded for 1 min have granular particle synthesis. It is expected to synthesize other functional alkali morphology with the size ranging from 1 to 10 ¯m, and large silicate ceramics with submicron- or nano- size particles via the agglomerations with particle about 1 ¯m in size, as shown in WASSR method. Figs. 4(a) and 4(b), respectively. The SEM images of the Li2SiO3 particles prepared using the WASSR method at 353 K for 60 min and SSR method are shown in Figs. 4(c) and 4(d). Li SiO References 2 3 1) T. E. Stanton, Proc. Am. Soc. Civ. Eng., 66, 17811811 (1940). particle obtained by the WASSR method has a granular particle ž ff 2) Z. P. Ba ant and A. Ste ens, Cem. Concr. Res., 30, 419 428 morphology and the particle size is less than 50 200 nm, while (2000). the particle size of the powder prepared by the SSR method 3) M. Thomas, B. Fournierb, K. Folliardc, J. Idekerc and M. was 1 micrometer size. The particles under 100 nm in diameter Shehatad, Cem. Concr. Res., 36, 18421856 (2006). synthesized by the WASSR method could be obtained without 4) T. Ichikawa, Cem. Concr. Res., 39, 716726 (2009). reference to the particle size of raw materials, as well as other 5) G. J. Butterworth, J. Nucl. Mater., 184, 197211 (1991).

474 Journal of the Ceramic Society of Japan 125 [6] 472-475 2017 JCS-Japan

6) T. Nakazawa, K. Yokoyama and K. Noda, J. Nucl. Mater., (Camb.), 51, 90939096 (2015). 258–263, 571575 (1998). 16) D. Cruz, S. Bulbulian, E. Limac and H. Pfeiffer, J. Solid State 7) M. Kato, S. Yoshikawa and K. Nakagawa, J. Mater. Sci. Lett., Chem., 179, 909916 (2006). 21, 485487 (2001). 17) M. J. Venegas, E. Fregoso-Israel, R. Escamilla and H. Pfeiffer, 8) M. Olivares-Marín, T. C. Drage and M. Mercedes Maroto- Ind. Eng. Chem. Res., 46, 24072412 (2007). Valer, Int. J. Greenhouse Gas Control, 4, 623629 (2010). 18) H. Pfeiffer, P. Bosch and S. Bulbulian, J. Nucl. Mater., 257, 9) K. Jackowska and A. R. West, J. Mater. Sci., 18, 23802384 309317 (1998). (1983). 19) M. Vinod and D. Bahnemann, J. Solid State Electrochem., 6, 10) B. Philippe, R. Dedryvère, J. Allouche, F. Lindgren, M. 498501 (2002). Gorgoi, H. Rensmo, D. Gonbeau and K. Edström, Chem. 20) J. Ortiz-Landeros, C. Gómez-Yáñez and H. Pfeiffer, J. Solid Mater., 24, 11071115 (2012). State Chem., 184, 22572262 (2011). 11) A. Veluchamy, C.-H. Doh, D.-H. Kim, J.-H. Lee, D.-J. Lee, 21) T. Kaneko, S. W. Kim, A. Toda, K. Uematsu, T. Ishigaki, K. K.-H. Ha, H.-M. Shin, B.-S. Jin, H.-S. Kim, S.-I. Moon and Toda, M. Sato, K. Uematsu, T. Ishigaki, J. Koide, M. Toda, Y. C.-W. Park, J. Power Sources, 188, 574577 (2009). Kudo, T. Masaki and D. H. Yoon, Sci. Adv. Mater., 7, 1502 12) Y. P. Naik, M. Mohapatra, N. D. Dahale, T. K. Seshagiri, V. 1505 (2015). Natarajan and S. V. Godbole, J. Lumin., 129, 12251229 22) K. Toda, S. W. Kim, T. Hasegawa, M. Watanabe, T. Kaneko, (2009). A. Toda, A. Itadani, M. Sato, K. Uematsu, T. Ishigaki, J. Koide, 13) I. Sabikoglu, M. Ayvacıkl, A. Bergeron, A. Ege and N. Can, M. Toda, Y. Kudo, T. Masaki and D. H. Yoon, Key Eng. Mater., J. Lumin., 132, 15971602 (2012). 690, 268271 (2016). 14) M. Xu, Q. Lian, Y. Wu, C. Ma, P. Tan, Q. Xia, J. Zhang, D. G. 23) A. Fernandez-Jimenez, I. Garcia-Lodeiro and A. Palomo, Ivey and W. Wei, RSC Advances, 6, 3424534253 (2016). J. Mater. Sci., 42, 30553065 (2007). 15) E. Zhao, X. Liu, H. Zhao, X. Xiao and Z. Hu, Chem. Commun.

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